Method for making breads

ABSTRACT

There has been a need to develop a method for preparing a bread dough using potassium bromate, an excellent bread improver, which provides baked breads free from residual bromate without affecting the flavor and taste of the breads. It has also been desired to develop a method for making breads using such a bread dough. The present invention provides a method for preparing a bread dough, which comprises incorporating potassium bromate as an aqueous solution, in combination with ferrous sulfate and ascorbic acid in the step of forming a sponge dough such that the solubility of the incorporated potassium bromate is increased in the bread dough to facilitate chemical decomposition of bromate, so that the resulting baked breads are free from residual bromate or have a reduced content of residual bromate. Also provided is a method for making breads, which comprises baking the bread dough.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a 37 C.F.R. § 1.53 (b) divisional of U.S.application Ser. No. 10/405,346 filed Apr. 3, 2003, which claimspriority on Japanese Application No. 2003/37637 filed Feb. 17, 2003. Theentire contents of these applications is here by incorporated byreference.

BACKGROUND OF THE INVENTION

The present invention relates to a method for making breads, morespecifically, by incorporating potassium bromate as an oxidizing agentinto a bread dough, wherein the resulting baked breads are free fromresidual bromate.

Potassium bromate has been widely used in the world since 1910s when itwas recommended as a bread improver in the United States. In Japan,there is a guideline for use of potassium bromate, stating that“potassium bromate is limited to use for yeast leavened bakery productsin an amount of up to 0.03 g (as bromate) per kg of wheat flour (i.e.,30 ppm based on wheat flour) and should be decomposed or removed beforecompleting final products,” that is, potassium bromate must not remainin the products after baking.

In conventional techniques, prevention of residual bromate in bakeryproducts has been accomplished, either by using sufficient time forfermentation and baking of a dough to ensure complete chemical reactionof bromate or by incorporating a reduced amount of potassium bromate, orboth.

The inventors of the present invention have already developed a methodfor prevention or reduction of residual bromate in bakery products byincorporating ascorbic acid (see, e.g., JP 8-116857 A).

The limitation “bromate should be decomposed or removed” or “bromatemust not remain” in the Japanese guideline is intended to mean thatbromate cannot be detected when measured by the most sensitive analysisat the time of the measurement, i.e., that bromate is below thedetection limit. In view of this limitation, the inventors of thepresent invention have attempted to incorporate ferrous sulfate in thestep of preparing a dough using potassium bromate and have succeeded inreducing residual bromate in bakery products to less than 3 ppb, anon-detectable level as measured by their developed ultra-sensitive HPLC(high performance liquid chromatography) analysis with a detection limitof 3 ppb for bromate in the baked breads (see, e.g., Japanese Patent No.3131898).

However, the term “free from residual bromate” or “prevention ofresidual bromate” as used herein is intended to mean that bromate doesnot remain in an amount greater than 1 ppb, the “detection limit forbromate” as measured by further improved state-of-the-art HPLC analysisat the filing of the present invention.

However, the above conventional techniques neither confirm theirefficacy for complete removal or significant reduction of residualbromate in breads, nor disclose the incorporation of potassium bromateas an aqueous solution. Further, in these conventional techniques,ferrous sulfate is incorporated in an amount of 50 ppm to 370 ppm basedon total wheat flour required to prepare a dough, which amountsignificantly exceeds the range acceptable for the breads of the presentinvention to maintain the loaf volume, flavor and taste of breads.

SUMMARY OF THE INVENTION

There has been a need to develop a method for preparing a bread doughwhich allows improvements in the quality of baked breads byincorporating potassium bromate into the bread dough and which providesbreads completely free from the incorporated bromate or with a bromatecontent reduced to less than 1 ppb, the detection limit for bromate. Ithas also been desired to develop a method for making breads using such abread dough.

The inventors of the present invention modified the above conventionaltechniques to use ferrous sulfate in an amount reduced to an acceptablerange to maintain the loaf volume, flavor and taste of baked breads,confirming very effective results in pullman type bread baked in coveredbaking pans because potassium bromate of even 15 ppm (possibly the upperlimit of the optimal range) produced no detectable residual bromate inthis type of bread, as measured by the analysis mentioned above.

In contrast, in open top bread baked in uncovered baking pans, it wasfound that residual bromate could be detected in an amount slightly overthe range discussed above.

The inventors of the present invention analyzed difference in residualbromate between breads baked in covered and uncovered baking pans, anddiscovered the following findings. The findings led to the completion ofthe present invention.

Namely, in the conventional techniques, potassium bromate in powder formwas incorporated into a bread dough. Potassium bromate has a relativelylow solubility in water. In open top bread, water would be evaporatedfrom the uncovered (i.e., exposed) upper surface of the dough in anearly stage of the baking step, followed by upper crust formation. As aresult, potassium bromate could not be completely dissolved into thebread dough near the upper surface before the completion of baking andhence it would remain near the upper crust upon completion of bakingbecause sufficient chemical decomposition of bromate would not occur.

The inventors of the present invention found that the above problemsassociated with conventional techniques could be overcome byincorporating potassium bromate in the step of preparing a bread doughsuch that the solubility of the incorporated potassium bromate isincreased in the bread dough to facilitate chemical decomposition ofbromate.

The present invention thus provides the following methods aimed atincorporating potassium bromate in the step of preparing a bread doughsuch that the solubility of the incorporated potassium bromate isincreased in the bread dough to facilitate chemical decomposition ofbromate. Namely, the present invention provides a method for preparing abread dough by the sponge and dough process, which comprisesincorporating potassium bromate as an aqueous solution, in combinationwith ferrous sulfate and ascorbic acid in the step of forming a sponge,so that the resulting baked breads are free from residual bromate, and amethod for making breads which comprises baking the bread dough.

Also provided are a method for preparing a bread dough which allowsimproved oven spring in the baking step and hence increased loaf volume,and a method for making breads which comprises baking the bread dough.

Further provided are a method for preparing a bread dough, whichcomprises incorporating a significantly reduced amount of ferroussulfate, so that the loaf volume, flavor and taste of baked breads arenot affected by ferrous sulfate, and a method for making breads whichcomprises baking the bread dough.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is therefore directed to a method for preparing abread dough by the sponge and dough process, which comprisesincorporating potassium bromate as an aqueous solution, in combinationwith ferrous sulfate and ascorbic acid in the step of forming a sponge,so that the resulting baked breads are free from residual bromate.

In the present invention, as stated below, it is necessary not only toprepare a bread dough by the sponge and dough process, but also toincorporate three ingredients, potassium bromate in aqueous solutionform, ferrous sulfate and ascorbic acid, in the step of forming asponge.

First, potassium bromate is incorporated in the form of an aqueoussolution prepared by dissolving powdered potassium bromate in water.This aqueous solution of potassium bromate may be prepared by simple orultrasonic stirring of potassium bromate in water or by any othertechnique for aqueous solution preparation.

For incorporation into a bread dough, potassium bromate should becompletely dissolved in water, but may be set to any desiredconcentration. Potassium bromate has a relatively low andtemperature-dependent solubility in water. It has a lower solubility ata lower temperature and its maximum solubility in water at 0° C. is 3%.Water temperature for bread dough preparation is usually higher than 0°C. and potassium bromate can be dissolved in an amount of 3% or more.However, an aqueous solution of potassium bromate should have aconcentration not higher than 3%, and in particular not higher than 2%,in order to avoid precipitation of potassium bromate during bread doughpreparation.

On the other hand, with respect to the lower concentration limit for anaqueous solution of potassium bromate, a lower concentration can beadvantageous in ensuring a higher solubility and more uniform dispersionof potassium bromate in a bread dough as well as in ensuring moreaccurate and easier metering of potassium bromate. However, too low aconcentration will affect handling and suitability for bread makingbecause there arises a need to incorporate a large volume of such anaqueous solution. The lower concentration limit may therefore beadjusted to meet both requirements.

An aqueous solution of potassium bromate may preferably be incorporatedin an amount of 8 ppm to 15 ppm (as potassium bromate) based on totalwheat flour required to prepare a bread dough. In the case of makingopen top bread, it is more preferably incorporated in an amount of 8 ppmto 12 ppm, and even more preferably 10 ppm to 12 ppm. In the case ofmaking pullman type bread, it is more preferably incorporated in anamount of 11 ppm to 15 ppm, and even more preferably 11 ppm to 13 ppm.This allows potassium bromate to sufficiently exhibit its inherentoxidizing effect, and as a result, a bread dough will have improved ovenspring when baked. Using such a bread dough achieves improvedbread-making properties such as increased loaf volume and improvedflavor of baked breads. Further, in both cases of pullman type and opentop breads, baked breads can be substantially free from residual bromateby merely incorporating a significantly small amount of ferrous sulfate.

Too small an amount of potassium bromate may fail to achieve theimproved bread-making properties mentioned above, while too large anamount of potassium bromate may also fail to achieve the improvedbread-making properties. In the case of too large an amount, it is alsonecessary to incorporate a larger amount of ferrous sulfate to achieveprevention of residual bromate in baked breads, particularly in open topbread. However, such a larger amount of ferrous sulfate will affect theloaf volume, flavor and taste of baked breads. Further, there stillremains a risk of residual bromate in baked breads even when a largeramount of ferrous sulfate is incorporated.

Ferrous sulfate has the chemical formula FeSO₄ and can be available incrystal (7-hydrate) or dry (1- to 1.5-hydrate) form, which aredesignated as ferrous sulfate (crystal) and ferrous sulfate (dry),respectively. In Japan, ferrous sulfate (crystal) was accepted as a foodadditive in 1957, followed by ferrous sulfate (dry) in 1964. They arecollectively referred to as ferrous sulfate.

Ferrous sulfate is prepared from iron and dilute sulfuric acid asfollows:Fe+H₂SO₄+7H₂O→FeSO₄.7H₂O(crystal)+H₂The dry form is prepared by drying the crystal thus prepared at 40° C.to give powder. Although ferrous sulfate as used herein may be in eithercrystal or dry form, the dry form (FeSO₄.1−1.5H₂O) was used in theExamples because of its higher purity.

When incorporated into a bread dough (including a sponge dough), ferroussulfate serves as a good iron enrichment in relation to the bread dough,while it serves as a reducing agent or its equivalent in relation topotassium bromate to ensure complete chemical reaction of bromate. Thepresent invention was completed based on this finding in principle.

Ferrous sulfate may preferably be incorporated in an amount of 10 ppm to20 ppm, more preferably 13 ppm to 17 ppm, and even more preferably 14ppm to 16 ppm, based on total wheat flour required to prepare a breaddough. On the precondition that potassium bromate is incorporated as anaqueous solution, such an amount of ferrous sulfate successfully ensuresprevention or reduction of residual bromate in baked breads (includingboth pullman type and open top breads), without affecting bread-makingproperties or the quality of baked breads. An amount of ferrous sulfateexceeding 16 ppm tends to slightly darken the crumb texture of bakedbread. An amount exceeding 20 ppm will affect, to a greater or lesserdegree, the loaf volume, flavor and taste of baked breads, depending onbread-making conditions. In contrast, an amount of ferrous sulfate lessthan 10 ppm may fail to ensure prevention or reduction of residualbromate in baked breads, depending on bread-making conditions.

According to the present invention, in addition to potassium bromate inaqueous solution form and ferrous sulfate, ascorbic acid is incorporatedin the step of forming a sponge of the bread dough. Ascorbic acid asused herein is intended to mean L-ascorbic acid.

When further incorporated into the bread dough, ascorbic acid ensuresnot only greater prevention of residual bromate in baked breads(including both pullman type and open top breads), but also greaterimprovements in bread-making properties and in the quality of bakedbreads. With respect to reduction of residual bromate, the bread doughof the present invention appears to contain Fe³⁺ generated from chemicaldecomposition of bromate by ferrous sulfate added thereto. However, Fe³⁺is difficult to chemically react with bromate. Ascorbic acid, whenincorporated into the bread dough, serves as a reducing agent not onlyto directly decompose bromate through chemical reaction, but also toindirectly contribute to additional chemical decomposition throughconversion of Fe³⁺ present in the bread dough (which is difficult tochemically react with bromate) into Fe²⁺ (which is easy to chemicallyreact with bromate).

Next, the improvements in bread-making properties and in the quality ofbaked breads will be explained as follows. Potassium bromate has verynarrow optimal ranges for amounts to be incorporated as well as fortemperatures and time for fermentation and baking to ensure that itsaction in a bread dough is sufficient. However, addition of ascorbicacid allows these optimal ranges to be extended, easing the conditionsfor bread making. Although incorporating breads (particularly pullmantype breads) with potassium bromate is more likely to cause caving, thisphenomenon can also be blocked by addition of ascorbic acid.

Ascorbic acid available for use may be uncoated ascorbic acid, ascorbicacid partially or completely coated with a fat, or ascorbic acidpartially or completely coated with a mixture of a fat and an emulsifiersuch as a mono-glyceride fatty acid ester.

Ascorbic acid may preferably be incorporated in an amount of 10 ppm to50 ppm based on total wheat flour required to prepare a bread dough. Inthe present invention, a larger amount of ascorbic acid will bedesirable in view of ensuring prevention of residual bromate in breads.More specifically, it is more preferably incorporated in an amount of 20ppm to 50 ppm, and even more preferably 30 ppm to 50 ppm. In contrast, asmaller amount of ascorbic acid will be desirable in view of ensuringimprovements in bread-making properties and in the quality of breads byallowing potassium bromate to exhibit its inherent oxidizing effect in abread dough. More specifically, it is more preferably incorporated in anamount of 10 ppm to 40 ppm, and even more preferably 10 ppm to 30 ppm.Thus, the most desirable amount of ascorbic acid used in the presentinvention can be 20 ppm to 30 ppm in view of meeting both requirements.

Preferably, either or both (more preferably both) of ferrous sulfate andascorbic acid may be incorporated in powder form, independently of theabove aqueous solution of potassium bromate. If ferrous sulfate is usedas an aqueous solution, the iron ion (Fe²⁺) in ferrous sulfate, capableof reacting with and decomposing bromate, would be affected and hencelose its ability to decompose bromate.

Likewise, if ascorbic acid is incorporated as an aqueous solution,potassium bromate would be decomposed before exhibiting its inherentoxidizing effect in a bread dough, which adversely affects improvementsin bread-making properties and in the quality of baked breads.

Ascorbic acid and ferrous sulfate may each be incorporated alone or as amixture with one or more members selected from yeast foods, enzymes,emulsifiers and other dough conditioners. Preferably, they may beincorporated as a mixture.

In the present invention, it is necessary not only to prepare a breaddough by the sponge and dough process, but also to incorporate threeingredients, potassium bromate in aqueous solution form, ferrous sulfateand ascorbic acid, in the step of forming a sponge.

The sponge and dough process refers to a technique for bread doughpreparation, which usually involves:

forming a sponge by mixing part of wheat flour required to prepare abread dough with yeast and water, optionally in combination with one ormore members selected from dough conditioners (e.g., yeast foods,oxidants, enzymes), emulsifiers, salt, and other materials or additives;

fermenting the sponge under given conditions;

making a dough by mixing the fermented sponge with the rest of the wheatflour, salt and water, optionally in combination with one or moremembers selected from sugars, fats, skimmed milk powder, and othermaterials or additives, to prepare a bread dough; and

fermenting (floor time) the bread dough under given conditions.

In the sponge and dough process of the present invention, the amount ofwheat flour used to form a sponge should be 50% to 80% by mass,preferably 60% to 80% by mass of total wheat flour required to prepare abread dough. If a larger or smaller amount of wheat flour is used toform a sponge, the resulting bread dough would lack fermentationstability and mechanical tolerance, which are features of the sponge anddough process.

In addition, the mixed sponge should be fermented at a temperature of26° C. to 29° C., preferably 27° C. to 28° C., for 4 to 6 hours,preferably 4 to 5 hours. If the sponge is fermented at a lowertemperature or for a shorter period of time, a young sponge would beformed and the resulting bread dough would lack fermentation stabilityand mechanical tolerance, which are features of the sponge and doughprocess. Such a young sponge would not only affect the quality ofbreads, but also give rise to insufficient chemical reaction amongpotassium bromate, ferrous sulfate and ascorbic acid. Likewise, if thesponge is fermented at a higher temperature or for a longer period oftime, an over-fermented old sponge would be formed and the resultingbread dough would also lack the above features of the sponge and doughprocess and affect the quality of breads.

Thus, the present invention requires an extended period of time for theentire process, from start of mixing (including sponge mixing) tocompletion of baking, and accordingly a longer period of time will beprovided for chemical reaction among potassium bromate, ferrous sulfateand ascorbic acid incorporated in the step of sponge mixing. As aresult, sufficient decomposition of bromate will occur to ensureprevention of residual bromate in breads.

The present invention encompasses a method for making breads, whichcomprises baking the bread dough prepared by the method for preparing abread dough discussed above.

The term “breads” as used herein is specifically intended to mean, butnot limited to, open top or pullman type breads obtained by baking abread dough placed in a rectangular baking pan having a rectangularbottom and 4 side walls standing upright from and surrounding thebottom. The bread dough is proofed before baking and optionally coveredwith a rectangular lid during baking.

The method of the present invention can be used to provide breads freefrom residual bromate, in both cases of pullman type and open topbreads. The method is particularly preferred for use in making open topbread baked in an uncovered baking pan.

Further, in the method for making breads of the present invention, thebread dough may be baked at low temperature, if desired. Morespecifically, this low temperature baking may be carried out under anatmosphere at 160° C. to 180° C. In general, the baking temperature forbreads is around 200° C. to 220° C. In the case of incorporatingpotassium bromate, in particular, it has been believed that a higherbaking temperature and a longer baking time are desirable for furtherreduction of residual bromate in breads. In contrast, the presentinvention allows prevention of residual bromate in breads, includingboth pullman type and open top breads, even at a baking temperature aslow as 160° C. to 180° C. Further, the period of time required forbaking at such a low temperature may be set to any value as long as itis not extremely shorter than that of conventional baking at thetemperature as mentioned above. However, for prevention of residualbromate in baked breads, it can be desirable to use a longer baking timethan that of conventional baking at the temperature as mentioned above.

Thus, the present invention is preferably adapted to a method for makingtender-type breads with an uncolored or light-colored and/or tendercrust. Of course, it is also preferred for tender-type open top breadwith such a crust.

If desired, the method of the present invention may further comprisespraying an aqueous solution of ferrous sulfate, an aqueous solution ofascorbic acid, an aqueous solution of ferrous sulfate and ascorbic acid,or water over the (upper) surface of the proofed bread dough beforebaking.

The above aqueous solution or water may be desirably sprayed in anamount of 3 to 7 g per 450 cm². Too small an amount per unit arearesults in a decrease in the reduction of residual bromate in breads,such as in the case of incorporating a larger amount of potassiumbromate. Too large an amount results in crusty breads with a hard(upper) surface crust, like a baguette, losing their characteristic softtexture. Likewise, even when sprayed in a larger amount, the aboveaqueous solution or water would not significantly enhance the reductionof residual bromate in breads. A unit area of 450 cm² corresponds to theupper open area (internal area) of a normal baking pan.

Thus, the present invention allows greater prevention of residualbromate in open top bread by spraying the above aqueous solution orwater over the surface of the proofed bread dough before baking, ascompared to open top bread baked without spraying. This embodiment istherefore extremely effective in incorporating a relatively large amountof potassium bromate.

As stated above, the present invention can provide breads free fromresidual bromate, i.e., those with a bromate content reduced to lessthan 1 ppb, the detection limit for bromate as measured by improved HPLCanalysis.

This HPLC analysis, which was developed by the inventors of the presentinvention as stated above, is an ultra-sensitive high performance liquidchromatography with a detection limit of 1 ppb for bromate in breads.Details of this analysis can be found on pages 221-224 of the Journal ofthe Food Hygienics Society of Japan, Vol. 43, No. 4 (August, 2002).

EXAMPLES

The present invention will be further described in the followingExamples and Test Examples, which are not intended to limit the scope ofthe invention.

Example 1 Making Open Top Bread

The amount of each ingredient is expressed as % by mass or ppm based ontotal wheat flour (the same applying hereinafter). (Ingredientcomposition) Sponge Wheat flour (strong flour)  70% Yeast  2% Doughconditioner (e.g., yeast food, 0.1% enzyme) including L-ascorbic acid(uncoated)  20 ppm Emulsifier 0.3% Water  40% Aqueous potassium bromatesolution 11.7 ppm (0.13% as concentration) (as potassium bromate)Ferrous sulfate  15 ppm Dough Wheat flour (strong flour)  30% Sugar  5%Fat  5% Skimmed milk powder  2% Salt  2% Water  25% (Process steps)Sponge Mixing Low speed 3 minutes, High speed 2 minutes Temperature ofmixed sponge 24° C. Fermentation 4 hours Dough Mixing Low speed 2minutes, High speed 3 minutes ↓ (add fat) Low speed 2 minutes, Highspeed 4.5 minutes Temperature of mixed dough 27° C. Floor time 20minutes Dividing 520 g Rounding 20 minutes Bench time Moulding (curleach sheeted dough into a roll) Panning (place two moulded rolls into abaking pan) Final proofing 38° C., 70 minutes Baking (uncovered) 170°C., 30 minutes

Open top bread was made under these conditions. Low temperature bakingwas carried out to give tender-type open top bread with a light-coloredtender crust.

(Evaluation)

Content of residual bromate was determined as described in the Journalof the Food Hygienics Society of Japan, supra.

(Result)

The bread was evaluated for the content of residual bromate as describedabove (detection limit: 1 ppb, the same applying hereinafter),indicating that residual bromate was non-detected (ND, the same applyinghereinafter).

This demonstrates that the present invention allows prevention ofresidual bromate in open top bread by incorporating potassium bromate asan aqueous solution, in combination with a much smaller amount offerrous sulfate (about 10-fold less than that of the conventionaltechniques) and an appropriate amount of ascorbic acid.

The open top bread thus prepared was found to show improved oven springand increased loaf volume in the baking step, as well as having goodloaf volume, flavor and taste which were not affected by ferroussulfate.

Examples 2 to 6 Ingredient Composition

The same ingredients as shown in Example 1 were used, except that anaqueous potassium bromate solution was incorporated in an amount aspotassium bromate of 8 ppm (Example 2), 9 ppm (Example 3), 10 ppm(Example 4), 11 ppm (Example 5) or 13 ppm (Example 6).

(Process Steps)

The same steps as shown in Example 1 were repeated.

(Results)

The open top bread from each example was evaluated for the content ofresidual bromate as described above, indicating that residual bromatewas ND in Examples 2 to 5 and 1.4 ppb in Example 6.

The open top bread thus prepared was found to show improved oven springand increased loaf volume in the baking step, as well as having goodloaf volume, flavor and taste which were not affected by ferroussulfate.

Examples 7 to 9 Ingredient Composition

The same ingredients as shown in Example 1 were used, except thatL-ascorbic acid was incorporated in an amount of 30 ppm (Example 7), 40ppm (Example 8) or 50 ppm (Example 9).

(Process Steps)

The same steps as shown in Example 1 were repeated.

(Result)

The open top bread from each example was evaluated for the content ofresidual bromate as described above, indicating that residual bromatewas ND in each case of incorporating L-ascorbic acid in an amount of 30ppm, 40 ppm and 50 ppm.

This demonstrates that the present invention allows prevention ofresidual bromate in open top bread when L-ascorbic acid is incorporatedin an amount of 20 ppm (Example 1) to 50 ppm.

However, a larger amount of L-ascorbic acid, particularly 40 ppm or 50ppm, tended to give a stiff dough because gluten was more likely totighten up during mixing in the presence of a larger amount ofL-ascorbic acid, thus slightly inhibiting oven spring in the baking stepand making breads tough.

Example 10 Ingredient Composition & Process Steps

In Example 6 given above, where 13 ppm potassium bromate wasincorporated into the bread dough to produce 1.4 ppb residual bromate inthe open top bread, an aqueous ferrous sulfate solution (0.1% asconcentration, 5 g) was sprayed over the uncovered upper surface (openarea of a baking pan: about 450 cm²) of the proofed bread dough beforebaking.

(Result)

The open top bread was evaluated for the content of residual bromate asdescribed above, indicating that residual bromate was ND.

As is evident from this result, the present invention allows significantreduction, and hence prevention, of residual bromate in open top breadby spraying an aqueous ferrous sulfate solution over the surface of theproofed bread dough before baking, as compared to open top bread bakedwithout spraying. This embodiment is therefore extremely effective inincorporating a relatively large amount of potassium bromate.

Examples 11 to 13 Ingredient Composition & Process Steps

In Example 1 given above, the following solution (5 g) was sprayed overthe uncovered upper surface (open area of a baking pan: about 450 cm²)of the proofed bread dough before baking:

water (Example 11);

an aqueous L-ascorbic acid solution (0.1% as concentration) (Example12); or

a mixture of an aqueous ferrous sulfate solution (0.18% asconcentration) and an aqueous L-ascorbic acid solution (0.24% asconcentration)(Example 13).

(Result)

The open top bread from each example was evaluated for the content ofresidual bromate as described above, indicating that residual bromatewas ND in each of Examples 11 to 13.

Examples 14 to 15 Ingredient Composition & Process Steps

In Example 6 given above, where 13 ppm potassium bromate wasincorporated into the bread dough to produce 1.4 ppb residual bromate inthe open top bread, the bread dough was covered with a dome-type lidduring baking (Example 14). Example 6 was also modified to incorporate14.3 ppm potassium bromate into the bread dough, which was covered witha dome-type lid during baking (Example 15).

(Result)

The bread from each example was evaluated for the content of residualbromate as described above, indicating that residual bromate was ND ineach of Examples 14 and 15. This demonstrates that the present inventionallows complete prevention of residual bromate in bread by using adome-type lid during baking, as compared to open top bread baked in anuncovered baking pan. This embodiment is therefore extremely effectivein incorporating a relatively large amount of potassium bromate.

Example 16 Making Pullman Type Bread

(Ingredient composition) Sponge Wheat flour (strong flour)  70% Yeast 2% Dough conditioner (e.g., yeast food, 0.1% enzyme) includingL-ascorbic acid (uncoated) 20 ppm Emulsifier 0.3% Water  40% Aqueouspotassium bromate solution 15 ppm (0.13% as concentration) (as potassiumbromate) Ferrous sulfate 15 ppm Dough Wheat flour (strong flour)  30%Sugar  7% Fat  5% Skimmed milk powder  2% Salt  2% Water  28% (Processsteps) Sponge Mixing Low speed 3 minutes, High speed 2 minutesTemperature of mixed sponge 24° C. Fermentation 4 hours Dough Mixing Lowspeed 2 minutes, High speed 3 minutes ↓ (add fat) Low speed 2 minutes,High speed 6 minutes Temperature of mixed dough 27° C. Floor time 20minutes Dividing 500 g Bench time 20 minutes Moulding into M-shape (curleach sheeted dough into a M-shaped roll) Panning (place three M-shapedrolls into a baking pan) Final proofing 38° C., 50 minutes Baking(covered) 210° C., 33 minutes

Pullman type bread was made under these conditions.

(Evaluation)

Content of residual bromate was determined as described in the Journalof the Food Hygienics Society of Japan, supra.

(Result)

The bread was evaluated for the content of residual bromate as describedabove (detection limit: 1 ppb), indicating that residual bromate was ND.

This demonstrated that the present invention also allows prevention ofresidual bromate in pullman type bread by incorporating potassiumbromate as an aqueous solution even in an amount of 15 ppm (as potassiumbromate).

The pullman type bread thus prepared also had good loaf volume, flavorand taste which were not affected by ferrous sulfate.

Examples 17 to 18

The same ingredients as shown in Example 1 were used, except thatpotassium bromate was incorporated in an amount of 10.4 ppm (Example 17)or 7.8 ppm (Example 18), to make open top bread in the same manner asshown in Example 1. The open top bread from each example was evaluatedfor its loaf volume and specific volume and also evaluated for anextensogram of the fermented dough. Each result was expressed as themean of five samples for each example.

Table 1 shows the results obtained, along with the results ofComparative Test 2 below. TABLE 1 Comparative Example Example ExampleExample 3 1 17 18 Potassium bromate 11.7 11.7 10.4 7.8 (ppm) One loafvolume (ml) 1,155 1,173 1,122 1,109 Weight after baking 229.6 228.8229.9 231.1 (g) Specific volume 5.0 5.1 4.9 4.8 Extensogram of fermenteddough F value (B.U.) 577 627 616 608 E value (mm) 94 97 95 96 F/E 6.16.5 6.5 6.3

TEST EXAMPLES Comparative Test 1

The open top bread samples prepared in Example 1 above and ComparativeExamples 1 to 3 below were evaluated and compared for the content ofresidual bromate by improved HPLC analysis as mentioned above (which wasalso adapted to the following Comparative Tests).

(Ingredient Composition for Comparative Example 1)

The same ingredients as shown in Example 1 were used, except thatpotassium bromate was incorporated in powder form and that ferroussulfate and ascorbic acid were not incorporated.

(Ingredient Composition for Comparative Example 2)

The same ingredients as shown in Example 1 were used, except thatferrous sulfate and ascorbic acid were not incorporated. In thiscomparative example, potassium bromate was incorporated as an aqueoussolution.

(Ingredient Composition for Comparative Example 3)

The same ingredients as shown in Example 1 were used, except thatpotassium bromate was incorporated in powder form. In this comparativeexample, ferrous sulfate and ascorbic acid were incorporated.

(Process Steps for Comparative Examples 1 to 3)

The same steps as shown in Example 1 were repeated.

(Result)

The open top bread from each example was evaluated for the content ofresidual bromate as described above, indicating that residual bromatewas ND in Example 1. In contrast, residual bromate was 20.2 ppb, 12.7ppb and 6.2 ppb in Comparative Examples 1, 2 and 3, respectively. Thisdemonstrates that the present invention allows significant reduction,and hence prevention, of residual bromate in open top bread, as comparedto Comparative Examples 1 to 3.

Comparative Test 2

The open top bread samples prepared in Examples 1, 17 and 18 andComparative Example 3 were evaluated for their loaf volume and specificvolume and also evaluated for an extensogram of the fermented dough. InExamples 17 and 18, the same ingredients as shown in Example 1 wereused, except that potassium bromate was incorporated in an amount of10.4 ppm and 7.8 ppm, respectively. Each result was expressed as themean of five samples for each example.

(Result)

Table 2 shows the results obtained. TABLE 2 Comparative Example ExampleExample Example 3 1 17 18 Potassium bromate 11.7 11.7 10.4 7.8 (ppm) Oneloaf volume (ml) 1,155 1,173 1,122 1,109 Weight after baking 229.6 228.8229.9 231.1 (g) Specific volume 5.0 5.1 4.9 4.8 Extensogram of fermenteddough F value (B.U.) 577 627 616 608 E value (mm) 94 97 95 96 F/E 6.16.5 6.5 6.3

As shown in Table 2, when potassium bromate was incorporated in anamount of 11.7 ppm, both loaf and specific volumes of the open top breadwere larger in Example 1 according to the present invention than inComparative Example 3. In other words, the present invention requires asmaller amount of potassium bromate than Comparative Example 3 to obtainopen top bread of the same loaf and specific volumes.

Likewise, when potassium bromate was incorporated in an amount of 11.7ppm (Example 1), 10.4 ppm (Example 17) and 7.8 ppm (Example 18), both F(resistance) and E (extensibility) values of extensogram were higher inthese Examples than in Comparative Example 3 (11.7 ppm). In particular,the F (resistance) value was much higher in Examples 1, 17 and 18 thanin Comparative Example 3.

As is well known, potassium bromate serves as an oxidizing agent totoughen and tighten wheat gluten in a bread dough by its oxidizingaction, so that the bread dough attains elasticity and gas-holdingcapacity required for great expansion during final proofing and baking.As is evident from the F (resistance) and E (extensibility) values ofextensogram given above, in all of Examples 1, 17 and 18 according tothe present invention, potassium bromate even in an equal or smalleramount than used in Comparative Example 3 has a strong oxidizing effecton wheat gluten in a bread dough and hence provides the bread dough withgreat elasticity, gas-holding capacity, extensibility and flexibility.

Comparative Test 3

Open top bread was made in the same manner as shown in Example 1, exceptthat the dough conditioner (including L-ascorbic acid) and ferroussulfate were added in the dough mixing step rather than incorporatedinto the sponge (Comparative Example 4). The open top bread samplesprepared in Example 1 and Comparative Example 4 were evaluated andcompared for the content of residual bromate.

(Result)

The content of residual bromate in the open top bread was evaluated asdescribed above, indicating that residual bromate was ND in Example 1,but 10.4 ppb in Comparative Example 4.

This demonstrates that in preparing a bread dough by the sponge anddough process, prevention of residual bromate in open top bread can beaccomplished by incorporating three ingredients, potassium bromate inaqueous solution form, ferrous sulfate and ascorbic acid, in the step offorming a sponge.

The present invention provides a method for preparing a bread dough,which comprises incorporating potassium bromate as an aqueous solution,in combination with ferrous sulfate and ascorbic acid in the step offorming a sponge such that the solubility of the incorporated potassiumbromate is increased in the bread dough to facilitate chemicaldecomposition of bromate, so that the resulting baked breads are freefrom residual bromate. Also provided is a method for making breads,which comprises baking the bread dough.

According to the present invention, it is possible to provide a breaddough which allows improved oven spring in the baking step and henceincreased loaf volume. Also, a significantly reduced amount of ferroussulfate can be incorporated into the bread dough, so that the loafvolume, flavor and taste of baked breads are not affected by ferroussulfate. The method of the present invention is widely applicable tobread dough preparation.

1. A method for making open top bread, said method comprising:incorporating potassium bromate as an aqueous solution, as well asincorporating ferrous sulfate and ascorbic acid in powder formindependently of the aqueous solution of potassium bromate, in the stepof forming a sponge in the sponge and dough process to prepare a breaddough; and baking the bread dough in an uncovered baking pan; whereinthe baked bread produced from the bread dough has residual bromate at alevel below the detection limit of 1 ppb, as measured by improved HPLCanalysis, and the amounts of said potassium bromate, ferrous sulfate andascorbic acid are 8-15 ppm, 10-20 ppm, and 10-50 ppm, respectively,based on the total wheat flour required to prepare the bread dough. 2.The method according to claim 1, wherein the ascorbic acid is partiallyor completely coated with a fat or a mixture of a fat and amono-glyceride fatty acid ester.
 3. The method according to claim 1,wherein the bread dough is baked at a temperature of from 160 to 180° C.4. The method according to claim 1, wherein the bread has an uncoloredor light-colored crust.
 5. The method according to claim 1, wherein thepotassium bromate is incorporated in an amount of 10 ppm to 12 ppm basedon the total wheat flour required to prepare the bread dough.
 6. Themethod according to claim 1, wherein the ascorbic acid is incorporatedin an amount of 20 ppm to 30 ppm based on the total wheat flour requiredto prepare the bread dough.
 7. The method according to claim 1, whereinthe amount of wheat flour used to form a sponge ranges from 50 to 80% bymass of total wheat flour required to prepare a bread dough.
 8. Themethod according to claim 1, wherein the sponge is fermented in thesponge forming step at a temperature of 26° C. to 29° C.
 9. The methodaccording to claim 1, wherein the sponge is fermented in the spongeforming step for 4 to 6 hours.